Current shoe industry is a mature and developed industry. There are many kinds of shoe products, for example, casual shoes, sports shoes, long and short boots, rain boots, etc. Although the casual shoes, the sports shoes, and the long and short boots having uppers made of fabric, textile or natural leather can effectively discharge sweat from the user's feet, they cannot prevent penetration of water into an interior of the shoes. Further, although the casual shoes, the sports shoes, and the long and short boots having the uppers made of plastic leather can prevent penetration of water into the interior of the shoes, they cannot effectively discharge sweat from the user's feet, thereby causing the user's feet to feel hot and uncomfortable.
Rain boots, on the other hand, are injection molded from rubber. Although they have a waterproof function, they are stiff and heavy when worn, so that when the rain boots are worn for walking, they can cause a great burden and bending resistance on the user's feet, leading to discomfort. Moreover, the rubber rain boots cannot discharge sweat, thereby also causing the user's feet to feel hot and uncomfortable.
Shoes having moisture permeable and waterproof functions are also being developed nowadays, but the uppers of these shoes are made by sewing together several upper pieces. The sewing threads will rub against the user's feet, so that there is discomfort and presence of foreign body felt by the user's feet.